The mass shooting at a historic Charleston black church Wednesday night may mark the deadliest hate crime in South Carolina history, according to a prominent local historian.

A lone gunman shot and killed nine worshippers at a prayer meeting inside Emanuel AME Church, the first and oldest African Methodist Episcopal congregation in the South. A Facebook photo of the suspect arrested for the attack, 21-year-old Dylann Roof, shows a thin, blond-haired young man wearing symbols of white supremacy on his jacket.

The FBI is working the shooting as a hate crime.

“I don’t think there’s ever been anything like that here,” said historian Jack Bass, a professor emeritus at the College of Charleston. “I think it’s just unprecedented.”

While South Carolina has suffered a long history of racially motivated arson attacks at black churches, some as recently as the late 1990s, the state’s last mass slaying of this scale occurred 139 years ago during the Reconstruction Era, Bass said.

In July 1876, violence erupted in Hamburg, a small town across the Savannah River from Augusta. Following a confrontation between white farmers and the town’s African-American militia, an armed mob of white men laid siege to the community. Five black men were summarily executed.